easy to use USB key with crypto (OpenBSD)

i've started using an encrypted filesystem on my USB storage key under
OpenBSD. it's pretty easy using vnconfig -k, only you have to remember
your passphrase (and i don't think you can easily change it). based
on what this
mailing list post says and this howto, you should be able to get this working. i use a 64 MB version
of this key.

here's the script i use to manage the device, i keep it as $HOME/bin/crypto-usb: